<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Title</title>
  <style>
    * {
      padding: 0;
      margin: 0;
    }

    #root {
      width: 9.2rem;
      height: 4rem;
      background: skyblue;
      margin: 0.4rem auto;
    }
  </style>
</head>
<body>
<div id="root"></div>
</body>
<script>
  // 设计稿 75
  function adapter(){
    document.documentElement.style.fontSize = document.documentElement.clientWidth/10+"px";
  }
  adapter();
  window.onresize = adapter;
</script>
</html>